Circuit breaking plug



Aug. 10, 1943. H. wElNx-:R

i CIRCUIT BREAKING PLUG Filed 0G13. 26, 1942 Z J f jme/2?@ Har@ 6572er Patented Aug. 10, 1943 CIRCUIT BREAKING PLUG Harry Weiner, Chicago, Ill., assignor to Florio G.

Flosi, doing business as cago, Ill.

AAllied Industries, Chi- Application October 26,1942, Serial No. 463,337

' (ci. 20o-11s) Claims.

'I'his invention relates to that type of electric circuit breaking plugs which, when the circuit is overloaded, or when a "short is produced, will Y break the circuit and will return again to close the circuit when the latter is relieved of the load or the short One of the objects of the invention is to provide a simple and effective plug of this character, which will instantly break or interruptv the circuit When an overload is produced.

A further object is to provide in an improved plug of this character, two contact members or elements which, before the plug is ready for use,

or before it is inserted into the Wall socket or line,-

are normally in contact, but separate from each other, and which, when a current of predetermined strength is passed through the contacts, will fuse together, and they will remain in this condition, with the current flowing therethrough, until the circuit is subjected to an overload, or a short is established. The passing ofthe current through the normally separate contacts will cause the contacts to fuse together, by forming ateat.

The establishment of an overload or short after such fusing, will heat the contacts to a degree to melt the fused point, whereupon the electrodynamic principle involved will, .when the metal at the fused point is soft, force the flow of the current in an abnormal manner and cause it to act as a striking force at the point of least mechanical resistance, which is the fused point,`

causing the contacts to separate and open the circuit.

Shortly thereafter, and when the material in one of the contacts cools, the residual magnetism in the other contact and the inherent resilient properties of the first mentioned contact, will cause the contacts to again assume engagement. This action takes place so rapidly that the metal in one of the contacts will still be soft enough to cause the contacts to fuse together, forming the ,teat, which latter will be commensurate in size with the amount of the resistance caused by the appliance or attachment with which the circuit is employed. That is, the size of the teat or fused point between the contacts Will be controlled by the strength of the current employed.

Each time that the contacts are brought back into engagement, after being separated, a fused point Will be established, and a completely closed circuit will also be established through the plug.

Any suitable material which will accomplish the desired result may be employed, but vit has been found in practice that when one of the contacts is constructed of cold rolled steel and the other of cold rolled bi-metallic steel, they will operate effectively, one of the contacts being softenthan the other,` and the said other contact, being not only harder, but much thinner, will result in the establishment of a fusion of the two at the point Where they contact.

Such a plug will operate automatically and will last for a considerable length 0f time, and for a great number of separations and fusings together, according to the size, thickness and quality of the materials used.

To the attainment of these ends and the accomplishment of other new and useful objects as will appear, the invention consists in the features of novelty in substantially the construction, combination and arrangement of the several parts, hereinafter more fully described and claimed and shown in the accompanying drawing illustrating this invention, and in which:.

Fig. 1 is a top plan view of a plug of this character, constructed 'in accordance with the principles of this invention.

Fig. 2 is a vertical sectional view taken on line 2 2, Fig. 1.

Fig. 3 is a vertical sectional view taken on line 3-3, Fig. 1, showing the plug in condition for use.

Fig. 4 is a detail perspective view of one of the contact members.

Fig. 5 is a detail perspective view of the other contact member. l

Fig. 6 is a view, similar to Fig. 3, of a modified form of the invention.

Referring more particularly to the drawing,

' the numeral I0 designates, generally, a casing constructed of any suitable non-conducting material, and in which casing is provided a chamber II open at the upper end. The chamber is adapted to be closed in any suitable manner, such as by means of a transparent closure I2 seate within a. recess I3. The numeral I4 designates, generally, a contact member which is constructed of any suitable material, preferably cold rolled steel, and is bent or shaped to form a contact edge I5. This con.- tact member I4 is seated in a recess I6 inthe wall of the chamber I I, and is held in position in any suitable manner, such as by means of a contact terminal Il which passes through the wall of the housing or casing I0 and is secured to the contact I4 by one end entering an opening I8 in the contact, and with the end or extremity of the terminal upset, as at I 9.

Within the chamber I I is arranged another contact member 20 which is constructed of any suitable material, either bi-metal or cold rolled steel, and is considerably harder than the contact I4, and much thinner. This contact member is provided, preferably, with a deected base-A cured in position, its inherent resiliency will y cause it to engage the edge I5 of the contact I4, but will be separate. therefrom. When a current of predetermined strength is passed through the plug, the material from which the contact I4 is formed will become soft and the contact member will be fused thereto. This fusion` will remain intact so long as a normal current of predetermined strength passes through the plug. When, however, an abnormal current is passed through the plug, the vpoint of fusion will melt and the contact 120 will be disconnected from the contact I4. The action is that, when an abnormal current flows through the plug, the tendency is to kick the contact 20 away from the contact Ill, and this electrodynamic action will causethe contact member 2U to move from the position shown in solid lines to the position shown in dotted lines, in Fig. 3, thereby interrupting the current. As soon as the line is reduced to a normal current, the residual 'magnetismin the contact i4, together with the inherent resiliency of the contact 20, will cause the latter to be moved back into engagement with the contact I4, as shown in full lines in Fig. 3. The contact is initially passed through said members they will fuse together at said point of contact, and when said members, after they are fused together, are subjected to an abnormal current, the point of fusion will soften and one of said contact members will be forced away from the other contact member to interrupt the circuit, the residual magnetism in one of said contact'members after the separation of the members, and the inherent resiliency in the other contact member.operat ing, when said abnormalcy is relieved, to cause the contact members to be brought into engagement, said members then againv becoming fused together.

2. A circuit breaking plug embodying a casingA of non-conducting material having an open end, two contact members within the casing normally separate froml each other, but having a point lcontact engagement, contact terminals individual to said members and extending to the outside of the casing, the composition of .said contact members being such that -when a normal current is initially passed through said members they will fuse together at said point of contact, and when said members, after they are fused together. are subjected to anabnorma1 current, the point of fusion will soften and one of said contact members will be forced away from the other contact member ,to interrupt the circuit, the residual .magnetism in one of said contact members after the separation of the members, and the inherent resiliency in the other contact member operating, when said abnormalcy is relieved, to cause the contact members to be brought into engage- Ill being soft, and the-contact 20 being much 24 being of a considerable diameter with respect to the base 2I,'forming the narrow portions 25,

serves as an additional means for interrupting the current, as these points, under an abnormal load, will burn out.

In the form of the invention shown in Fig. 6,A

there is provided a manual means for moving the contact member 20 back into engagement with the contact It,4 so as to permit the two contacts to become fused together. Any suitable means maybe provided for that purpose, but a ment, said members then again becoming fused together, one of said contact members being substantially U-shaped in cross-section, to provide a narrowA edge' to be contacted by the other of said contact members. y

`3. A circuit breaking plug ,embodying a casing of non-conducting material, two contact members Within the casing normally separate from members, after they are'fused together, are subjected to an abnormal current, the point of fusion will'soften and one of said contact memsimple and eflicient'means embodies 'a shaft 26 having an arm 2l and a handle 28, the shaft 26 and arm 2'I beingfdisposed -within the chamber nation and arrangement of theseveral'parts,

within the scope of the claims, without departing from the spirit of this invention.

What is claimed as new is:

1. A circuit breaking plug embodying a casing of non-conducting material having an open end, two vcontact members .within the casing normally separate from each other, but'having a point contact engagement, contact terminals individwhen they are separated, whereby they may be of non-conducting material, two contact mem.

bers within the casingnormally-separate from eachother, but having a point contact engagement, contact terminals 'individual to the said members and leading tothe outsideof the casing, the composition of said contact members being such that when anormal current is rini--A tially passed through said members they will fuse together at said point of contact, and when said members, after they are fused together, are subjected to an abnormal current, the point of fusion will soften and one of said contact members will be forced away from the other contact member to interrupt the circuit, and means'sep'- ual to said members and etending to the outside arate from said contacts and accessible from the outside of said casing for positively causing the point of fusion will soften and one of said contact members will be forced away from the other contact member to interrupt the circuit,

the residual magnetism in one of said contactmembers after the separation of the members, and the inherent resiliency in the other contact member operating, when said abnormalcy is relieved, to cause the contact members to be brought into engagement, said members then again becoming fused together.

HARRY WEINER. 

